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The Humongous Fungus

Beneath the soil in the Malheur National
Forest in eastern Oregon, the United States, lurks a very large fungus
that has been slowly weaving its way through the roots of trees for
centuries to become the single largest living organism known to humans.

The fungus, Armillaria solidipes, remains
mostly underground, hidden from sight, but every autumn just after the
rains it sends up clusters of small yellow-brown mushrooms from the
bases of trees it has infected. These mushrooms, commonly called “honey
mushrooms”, are the most visible part of the fungus seen by the casual
observer. The bulk of the fungus lies underneath the forest floor—a vast
network of black filament-like structures called rhizomorphs, that
creep through the soil, feeling out new root systems to colonize. The
underground growth can stretch up to several square kilometers. The
specimen in Malheur National Forest covers 2,200 acres (8.9 square
kilometer), and has been named the “Humongous Fungus”. Another specimen,
also named the “Humongous Fungus”, resides in a forest in Michigan’s
Upper Peninsula. That one is spread over 37 acres.The honey mushroom is the above-ground part of a vast subterranean fungus. Photo credit: Dan Molter/Wikimedia
Michigan’s
Humongous Fungus was discovered in the early 1990s by a team of
researchers working on an unrelated project studying the biological
effects of extremely low frequency radio emissions on wildlife in the
Upper Peninsula of Michigan. In one particular area of the forest, Armillaria
had infected pine trees that loggers had planted years after they
removed a batch of infected oak trees. When the researchers collected
samples of the fungus from a widespread area and analyzed the DNA, the
specimens they collected turned out to be from a single organism.
Before
the Humongous Fungus was discovered, mycologists knew that a fungus
could grow to be quite large, but no one expected them to grow as large
as 37 acres of land. Less than a decade later, a team of researchers
from the US Forest Service, trying investigate the cause of a large
number of tree deaths in the Malheur National Forest in east Oregon,
discovered another Armillaria colony. This one was spread over a
phenomenal area—2,200 acres. The fungus was not only large but also
very old with date ranging from 2,400 years to 8,500 years.
Scientists are still not sure of all the factors that allow these funguses to become so large and old. Typically, the Armillaria spreads
from one tree to another by means of an extensive subterranean network
of rhizomorphs, which are black root-like structures. The rhizomorph
attach themselves to the roots of living and sometimes dead plants and
sap nutrients out of them. They grow just beneath the soil at the rate
of approximately 1 meter a year spreading infection from one tree to
another even if the trees are spaced out over a large distance. These
rhizomorphs give the Armillaria enough competitive advantage
over other fungi species. Over the course of several centuries the
fungus can expand over vast areas.
The Armillaria fungus
isn’t rare. They can be found in forests around the world in North
America, Europe, and Asia. So its very possible that even more humongous
funguses will be discovered in the future.
If the Humongous
Fungus of the Malheur National Forest is considered a single organism,
it is the largest known organism in the world by area, and rivals the
aspen grove "Pando" as the single largest organism with the highest living biomass.
Rhizomorphs of the Armillaria
fungus propagating up into the wood of a tree. When fresh these
rhizomorphs are cream colored but darken to brown or black as they age.
Photo credit: nhgardensolutions.wordpress.com
Photo credit: nhgardensolutions.wordpress.com
Photo credit: Eric/Wikimedia
Honey mushrooms in a forest near Elgin Street, Ontario, Canada. Photo credit: Paul Derbyshire/Wikimedia
Sources: Wikipedia / Wikipedia / Wikipedia / Smells Like Science / USDA
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The Humongous Fungus
Reviewed by photofun4ucom
on
July 08, 2017
Rating: 5